A lot of theories in this thread are based on some assumptions that are not correct to me:
1. Binary Code
It is assumed that the four symbols in the corners stand for binary code. These symbols are translated into 001 010 011 100 or 110 101 100 011.
a) Whichever interpretation you might use, at least one of the binary numbers start with a leading zero. This is not natural scientific. If I would be to start conversation with an alien species, I would not use leading zeroes, as they are simply unnecessary.
b) Although the symbol in the center depicts a circle, the binary code does _not_ state a clockwise or anticlockwise numbering, but crossing instead. The easiest way to draw a circle is by using its radius. You draw it clockwise or anticlockwise. You don't draw a quarter circle and then the opposite quarter. It would have been easy to arrange the binary numbers in either way.
-> This is why I don't think these symbols are binary.
2. Lower left lines
The lines in the lower left are assumed to be connected to the circle.
This is not true. At least the line that is more to the 180 degree position is not connected to circle. Take a close look at the spectrogramms linked on the first page. There is a gap between the line and the circle.
I don't have a clue what this means, but if I wanted somebody to measure an angle, I would make sure both lines connect to the circle.
3. Triplets in Purrs / Chirps
If you assume the symbols in the corner are binary numbers, why do you use triplets (i.e. three bits)? Triplets could represent numbers 0-7, which are outside the - assumed - binary numbers in the corners. Why don't you use 2 bits? They represent the numbers 0-3, which could translate to corners 1-4 (with an offset of 1).
The purrs are not devided into triplets. And although most of the chirps seem to be triplets, there are some that have more "bits" to it.
Of course you can insist that these points are inaccuracies of the entity that made that image.
But then I could also argue that the radial line in the lower right _were meant_ to be at 45 degrees, and the lines in the lower left _were meant_ to be touching the circle and crossing the center of the circle, as both are just slight inaccuracies.
I don't buy that. I don't make the assumption that some graphics designer at FD made some mistake or was simply erratic at creating these images.
FD has proven multiple times, that they do care about science. And especially in this story line I simply expect FD to deliver correct work. Otherwise they would have patched it already.